9 research outputs found
The Structural and Magnetic Properties of Zn0.8â4x Dy x O y (0.05â€xâ€0.10) Compounds Prepared by Solid-State Reactions
Optical, Structural, and Magnetic Properties of ZnO:Co Nanoparticles Prepared by a Thermal Treatment of Ball Milled Precursors
Valency configuration of transition metal impurities in ZnO
We use the self-interaction corrected local spin-density approximation to
investigate the ground state valency configuration of transition metal (TM =
Mn, Co) impurities in n- and p-type ZnO. We find that in pure Zn1-xTMxO, the
localized TM2+ configuration is energetically favored over the itinerant
d-electron configuration of the local spin density (LSD) picture. Our
calculations indicate furthermore that the (+/0) donor level is situated in the
ZnO gap. Consequently, for n-type conditions, with the Fermi energy eF close to
the conduction band minimum, TM remains in the 2+ charge state, while for
p-type conditions, with eF close to the valence band maximum, the 3+ charge
state is energetically preferred. In the latter scenario, modeled here by
co-doping with N, the additional delocalized d-electron charge transfers into
the entire states at the top of the valence band, and hole carriers will only
exist, if the N concentration exceeds the TM impurity concentration